Re: behavior of regexp ( ) function

[David Bateman]

David Bateman wrote:
> Thanks Soren and Benjamin, I believe the attached patch will do the 
> right thing though I'm not sure why PCRE wants to return a zero length 
> match for a pattern like "[^\t]*". Best just to ignore such matches 
> rather than make them abort the search for matches as the code 
> previously did. Patch pushed and attached
>
> D.
This time it really is attached :-)

D.


--
David Bateman                                address@hidden
35 rue Gambetta                              +33 1 46 04 02 18 (Home)
92100 Boulogne-Billancourt FRANCE            +33 6 72 01 06 33 (Mob)

# HG changeset patch
# User David Bateman <address@hidden>
# Date 1233182607 -3600
# Node ID c8c212126d6d8aa02f048ae26c5703ec14b8168b
# Parent  07af3245452d2b62deb68c9ecb73d5c3905ba51d
For zero length matches in regexp, advance index by one and try again

diff --git a/src/ChangeLog b/src/ChangeLog
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,3 +1,9 @@
+2008-01-28  David Bateman  <address@hidden>
+
+       * DLD-FUNCTIONS/regexp.cc (octregexp_list): Don't break for zero
+       length match, but rather advance the index by one character and
+       try again.
+
 2009-01-28  Jaroslav Hajek  <address@hidden>
 
        * DLD-FUNCTIONS/lookup.cc (Flookup): Fix doc string.
diff --git a/src/DLD-FUNCTIONS/regexp.cc b/src/DLD-FUNCTIONS/regexp.cc
--- a/src/DLD-FUNCTIONS/regexp.cc
+++ b/src/DLD-FUNCTIONS/regexp.cc
@@ -314,7 +314,7 @@
 
                      for (; i < max_length + 1; i++)
                        {
-                         buf <<pattern.substr(new_pos, tmp_pos3 - new_pos)
+                         buf << pattern.substr(new_pos, tmp_pos3 - new_pos)
                              << "{" << i << "}";
                          buf << pattern.substr(tmp_pos3 + 1, 
                                                tmp_pos1 - tmp_pos3 - 1);
@@ -421,7 +421,11 @@
          else if (matches == PCRE_ERROR_NOMATCH)
            break;
          else if (ovector[1] <= ovector[0])
-           break;
+           {
+             // FIXME: Zero sized match!! Is this the right thing to do?
+             idx = ovector[0] + 1;
+             continue;
+           }
          else
            {
              int pos_match = 0;
@@ -515,6 +519,9 @@
              int matches = 0;
              while (matches < subexpr && match[matches].rm_so >= 0) 
                matches++;
+
+             if (matches == 0 || match[0].rm_eo == 0)
+               break;
 
              s = double (match[0].rm_so+1+idx);
              e = double (match[0].rm_eo+idx);